This comes as Austrian tanks have moved to seal off a vital border with Italy as over 84,000 migrants from North African have reached Italian shores this year – a 19 per cent increase from last year according to the UN.

Spain is also struggling to cope with the crisis with 6,000 people arriving by boat this year and dozens drowning during the treacherous journey.

Speaking with German news outlet Welt am Sonntag newspaper, US billionaire Gates, 61, said developed nations should instead be spending more on foreign aid to treat the causes of migration.

He said: “On the one hand you want to demonstrate generosity and take in refugees.

“But the more generous you are, the more word gets around about this — which in turn motivates more people to leave Africa.

“Germany cannot possibly take in the huge number of people who are wanting to make their way to Europe.”